In recent years, mobile electronic equipments such as notebook personal computer, mobile phone and the like rapidly spread along with the technical advances of the communication systems, and the performances thereof are improved year by year. In particular, power consumptions of the mobile equipments are in upward trend corresponding to enhancements of the performances. Thus, requirements such as higher energy density, higher output and the like are enhanced for battery cells that function as electric sources thereof.
Lithium ion batteries were invented for battery cell for higher energy density, and have been widely employed after 1990s. Typical lithium ion battery in this era employed electrode active materials, which were typically, for example, lithium-containing transition metal oxide such as lithium manganese oxide, lithium cobalt oxide and the like employed for a positive electrode, and carbon for a negative electrode. In such type of lithium ion battery, charging and discharging is conducted by utilizing insertion/elimination reactions of lithium ion for such electrode active material. Such lithium ion battery exhibits larger energy density and better cycle characteristics, and therefore are utilized in various types of electronic equipments such as mobile telephones and the like. However, since a rate of an electrode reaction in such lithium ion battery is lower, characteristics of battery cell are considerably deteriorated when larger electric current is extracted. Therefore, there were drawbacks of difficulty in providing larger output and requiring longer time for charging.
Electric double layer capacitors are known as capacitor devices that can provide larger output. Such electric double layer capacitor is capable of discharging larger electric current at a time, and therefore can output larger power. Further, such electric double layer capacitor exhibits better cycle characteristics, and thus further developments proceeds for backup power sources. However, such capacitor also exhibits significantly lower energy density and miniaturization thereof is difficult, and therefore is not suited for the use in power sources of mobile electronic equipments.
For the purpose of obtaining electrode material having larger energy density and smaller weight, battery cells employing sulfur compounds or organic compounds as electrode active materials has also been developed. For example, Patent Document 1 (U.S. Pat. No. 4,833,048) and Patent Document 2 (Japanese Patent No. 2,715,778) disclose battery cells employing organic compounds having disulfide bond for a positive electrode. These utilize electrochemical redox reaction involving creation and dissociation of disulfide bond as a basis for battery cells. Such battery cell is composed of electrode materials containing chemical elements of smaller specific gravities such as sulfur, carbon and the like, and thus is a high capacity battery cell having higher energy density. However, due to lower efficiency for recombination of dissociated bond and diffusion of electrode active materials into an electrolytic solution, there is a drawback of easy decrease of capacitance for a number of charging and discharging cycles.
On the other hand, battery cells employing electroconductive polymers for electrode materials are proposed as battery cells that utilize organic compounds. These are battery cells that utilize doping and de-doping reactions of electrolyte ions for the electroconductive polymers. The doping reaction is a chemical reaction, in which charged radical generated through an oxidization or a reduction of an electroconductive polymer is stabilized by counter ion. Patent Document 3 (U.S. Pat. No. 4,442,187) discloses a battery cell that utilizes such electroconductive polymer for materials of the positive electrode or the negative electrode. Such battery cell is composed of chemical element having smaller specific gravity such as carbon and nitrogen, and was expected to be employed as a high capacity battery cell. However, in the electroconductive polymer, charged radicals generated by an oxidoreduction are delocalized over wider area of π conjugated system, and these radicals typically interact to cause electrostatic restitution or dissipation of radical. This causes limitation on generation of charged radical, or in other words, to doping concentration, and thus provides limitation on the capacitance of the battery cell. For example, it is reported that doping ratio in a battery cell employing poly aniline for a positive electrode is equal to or lower than 50%, and is 7% in case of poly acethylene. In the battery cell employing the electroconductive polymer as the electrode material, while a certain advantageous effect is obtained in terms of weight reduction, no battery cell having larger energy density is obtained.
Battery cells employing an oxidation-reduction reaction of a radical compound are proposed as battery cells employing an organic compound as an electrode active material for the battery cell. For example, Patent Document 4 (Japanese Patent Laid-Open No. 2002-151,084) discloses organic radical compounds such as nitroxide radical compounds, aryloxy radical compounds and polymer compounds having certain type of amino triazine structure as active materials, and in addition, a battery cell employing an organic radical compound for a material of a positive electrode or a negative electrode is disclosed. Further, Patent Document 5 (Japanese Patent Laid-Open No. 2002-304,996) discloses capacitor devices employing nitroxide compounds, in particular compounds having cyclic nitroxide structure, as an electrode active material. In addition, polyradical compounds employed for the electrode active material therein is synthesized by polymerizing 2,2,6,6-tetramethylpiperidine methacrylate with a polymerization initiator of azobisisobutyronitrile, and then oxidizing the polymerized compound with m-chloroperbenzoic acid. On the other hand, Patent Document 6 (Japanese Patent Laid-Open No. 2002-313,344) discloses a battery cell employing nitroxyl radical polymer, which is a polyradical compound, as a binder for electrodes.
On the other hand, processes for synthesizing vinyl ethers such as vinyl ether, divinyl ether, trivinyl ether and the like are known, which typically comprise a process for reacting acetylene and associated alcohol under a pressure (about 20-50 atom) in the presence of potassium hydroxide and sodium hydroxide at catalyst quantities at higher temperature (180 to 200 degree C.) (Non-Patent Document 1); a process for thermally refluxing associated alcohol and alkyl vinyl ether in the presence of mercuric acetate catalyst (Non-Patent Document 2); and a process for thermally refluxing associated alcohol and vinyl acetate in the presence of iridium catalyst (Non-Patent Document 3 and Patent Document 7).    [Patent Document 1]    U.S. Pat. No. 4,833,048    [Patent Document 2]    Japanese Patent No. 2,715,778    [Patent Document 3]    U.S. Pat. No. 4,442,187    [Patent Document 4]    Japanese Patent Laid-Open No. 2002-151,084    [Patent Document 5]    Japanese Patent Laid-Open No. 2002-304,996    [Patent Document 6]    Japanese Patent Laid-Open No. 2002-313,344    [Patent Document 7]    Japanese Patent Laid-Open No. 2003-73,321    [Non-Patent Document 1]    Reppe, W., et al., Liebigs Ann. Chem., volume 601, pp. 81-111 (1956)    [Non-Patent Document 2]    Warren, H., Journal of The American Chemical Society, volume 79, pp. 2828-2833 (1957)    [Non-Patent Document 3]    Ishii, Y, Journal of The American Chemical Society, volume 124, pp. 1590-1591 (2002)